5G new radio uplink intermodulation distortion mitigation

ABSTRACT

The disclosed technology provides a system and method for determining an uplink (UL) waveform for a mobile device to use for UL transmission in carrier aggregation or dual connectivity modes, where the UL waveform is selected to eliminate or minimize the deleterious effects of intermodulation distortion (IMD). The system identifies frequency bands scheduled for use by the mobile device for concurrent UL transmissions and for DL transmissions and determines if the combination of frequency bands can lead to high IMD. If the combination can lead to high IMD, the system can instruct the mobile device to switch to a Discrete Fourier Transform (DFT)-spread Orthogonal Frequency Division Multiplexing (OFDM) (DFT-s-OFDM) waveform for UL transmissions; if the combination would not likely lead to high IMD, the system can instruct the mobile device to switch to a Cyclic Prefix OFDM (CP-OFDM) waveform for the UL transmissions.

BACKGROUND

5G New Radio (NR) is expected to coexist with 4G Long Term Evolution(LTE) or E-UTRAN (Evolved-UMTS Terrestrial Radio Access Network) systemsboth during the initial deployment phase (providing a seamlesstransition from 4G LTE to 5G NR) and even later when 5G is widelydeployed nationwide. For example, heterogenous networks (HetNets)providing for E-UTRAN-NR Dual Connectivity (EN-DC) will exist toprovide, for example, better in-building connectivity and indoorcoverage using user equipment or terminal equipment simultaneouslyconnected to 5G small cell devices and 4G macro base stations orvice-versa.

However, some of the band combinations that will be aggregated between5G NR and 4G LTE will create high levels of intermodulation power inspecific bands. This intermodulation power will create intermodulationdistortion (IMD) which can desensitize the receiver, degrade thetransmitted uplink (UL) and downlink (DL) signals, lead to a loss ofspectrum efficiency, and lead to service quality issues to mobileoperator subscribers. It is therefore beneficial to mitigate the effectsof intermodulation distortion on aggregated bands, including IMD arisingfrom 4G and 5G co-existence, and in mobile devices operating in LTE andNR standalone (SA) dual connectivity and carrier aggregation modes.

BRIEF DESCRIPTION OF THE DRAWINGS

Detailed descriptions of implementations of the present invention willbe described and explained using the accompanying drawings.

FIG. 1 is a block diagram that illustrates a wireless communicationssystem.

FIG. 2 is a block diagram that illustrates an example of a computersystem in which at least some operations described herein can beimplemented.

FIG. 3 is a block diagram of a representative environment where thedynamic waveform switcher function can operate.

FIG. 4 is a representative flow diagram illustrating a method fordetermining waveforms for uplink (UL) transmissions,

The technologies described herein will become more apparent to thoseskilled in the art from studying the Detailed Description in conjunctionwith the drawings. Embodiments or implementations describing aspects ofthe invention are illustrated by way of example, and the same referencescan indicate similar elements. While the drawings depict variousimplementations for the purpose of illustration, those skilled in theart will recognize that alternative implementations can be employedwithout departing from the principles of the present technologies.Accordingly, while specific implementations are shown in the drawings,the technology is amenable to various modifications.

DETAILED DESCRIPTION

In one example aspect of the disclosed technology, a wirelesscommunications network identifies uplink (UL) frequency resourcesscheduled to a mobile device or user equipment (UE) for concurrent ULtransmissions, e.g., multiple-uplink carrier aggregation (CA) ordual-connectivity (DC) transmissions. The network also identifiesdownlink (DL) frequency resources scheduled to the mobile device for DLtransmission. The network then determines, based on the UL and DLfrequency resources, if there is a high risk of IMD from the ULfrequency resources falling in the DL frequency resources. If there is ahigh risk, the system can notify the mobile device to switch to aDiscrete Fourier Transform (DFT)-spread Orthogonal Frequency DivisionMultiplexing (OFDM) (DFT-s-OFDM) waveform for the concurrent ULtransmissions. On the other hand, if the risk is not high, the systemcan notify to mobile device to switch to or remain on a Cyclic Prefix(CP) OFDM (CP-OFDM) waveform for the concurrent UL transmissions.

In another example aspect of the disclosed technology, a processor orserver in the network queries a memory or database in the network, wherethe query includes the UL frequency bands (e.g., the frequency bands ofUL component carriers scheduled or granted for use by the mobile device)and DL frequency band(s). The processor or server returns a queryresponse with data from the database or memory which the network can useto identify the UL waveforms or UL access schemes for use by the mobiledevice for concurrent UL transmissions.

The description and associated drawings are illustrative examples andare not to be construed as limiting. This disclosure provides certaindetails for a thorough understanding and enabling description of theseexamples. One skilled in the relevant technology will understand,however, that the invention can be practiced without many of thesedetails. Likewise, one skilled in the relevant technology willunderstand that the invention can include well-known structures orfeatures that are not shown or described in detail, to avoidunnecessarily obscuring the descriptions of examples.

Wireless Communications System

FIG. 1 is a block diagram that illustrates a wireless telecommunicationsystem 100 (“system 100”) in which aspects of the disclosed technologyare incorporated. The system 100 includes base stations 102-1 through102-4 (also referred to individually as “base station 102” orcollectively as “base stations 102”). A base station is a type ofnetwork access node (NAN) that can also be referred to as a cell site, abase transceiver station, or a radio base station. The system 100 caninclude any combination of NANs including an access point, radiotransceiver, gNodeB (gNB), NodeB, eNodeB (eNB), Home NodeB or eNodeB, orthe like. In addition to being a WWAN base station, a NAN can be a WLANaccess point, such as an Institute of Electrical and ElectronicsEngineers (IEEE) 802.11 access point.

The NANs of a network formed by the system 100 also include wirelessdevices 104-1 through 104-8 (referred to individually as “wirelessdevice 104” or collectively as “wireless devices 104”) and a corenetwork 106. The wireless devices 104-1 through 104-8 can correspond toor include network entities capable of communication using variousconnectivity standards. For example, a 5G communication channel can usemillimeter wave (mmW) access frequencies of 28 GHz or more. In someimplementations, the wireless device 104 can operatively couple to abase station 102 over an LTE/LTE-A communication channel, which isreferred to as a 4G communication channel.

The core network 106 provides, manages, and controls security services,user authentication, access authorization, tracking, Internet Protocol(IP) connectivity, and other access, routing, or mobility functions. Thebase stations 102 interface with the core network 106 through a firstset of backhaul links 108 (e.g., S1 interfaces) and can perform radioconfiguration and scheduling for communication with the wireless devices104 or can operate under the control of a base station controller (notshown). In some examples, the base stations 102 can communicate, eitherdirectly or indirectly (e.g., through the core network 106), with eachother over a second set of backhaul links 110-1 through 110-3 (e.g., X1interfaces), which can be wired or wireless communication links.

The base stations 102 can wirelessly communicate with the wirelessdevices 104 via one or more base station antennas. The cell sites canprovide communication coverage for geographic coverage areas 112-1through 112-4 (also referred to individually as “coverage area 112” orcollectively as “coverage areas 112”). The geographic coverage area 112for a base station 102 can be divided into sectors making up only aportion of the coverage area (not shown). The system 100 can includebase stations of different types (e.g., macro and/or small cell basestations). In some implementations, there can be overlapping geographiccoverage areas 112 for different service environments (e.g.,Internet-of-Things (loT), mobile broadband (MBB), vehicle-to-everything(V2X), machine-to-machine (M2M), machine-to-everything (M2X),ultra-reliable low-latency communication (URLLC), machine-typecommunication (MTC)), etc.

The system 100 can include a 5G network and/or an LTE/LTE-A or othernetwork. In an LTE/LTE-A network, the term eNB is used to describe thebase stations 102 and in 5G new radio (NR) networks, the term gNBs isused to describe the base stations 102 that can include mmWcommunications. The system 100 can thus form a heterogeneous network inwhich different types of base stations provide coverage for variousgeographical regions. For example, each base station 102 can providecommunication coverage for a macro cell, a small cell, and/or othertypes of cells. As used herein, the term “cell” can relate to a basestation, a carrier or component carrier associated with the basestation, ora coverage area (e.g., sector) of a carrier or base station,depending on context.

A macro cell generally covers a relatively large geographic area (e.g.,several kilometers in radius) and can allow access by wireless deviceswith service subscriptions with a wireless network service provider. Asindicated earlier, a small cell is a lower-powered base station, ascompared with a macro cell, and can operate in the same or different(e.g., licensed, unlicensed) frequency bands as macro cells. Examples ofsmall cells include pico cells, femto cells, and micro cells. Ingeneral, a pico cell can cover a relatively smaller geographic area andcan allow unrestricted access by wireless devices with servicesubscriptions with the network provider. A femto cell covers arelatively smaller geographic area (e.g., a home) and can providerestricted access by wireless devices having an association with thefemto cell (e.g., wireless devices in a closed subscriber group (CSG),wireless devices for users in the home). A base station can support oneor multiple (e.g., two, three, four, and the like) cells (e.g.,component carriers). All fixed transceivers noted herein that canprovide access to the network are NANs, including small cells.

The communication networks that accommodate various disclosed examplescan be packet-based networks that operate according to a layeredprotocol stack. In the user plane, communications at the bearer orPacket Data Convergence Protocol (PDCP) layer can be IP-based. A RadioLink Control (RLC) layer then performs packet segmentation andreassembly to communicate over logical channels. A Medium Access Control(MAC) layer can perform priority handling and multiplexing of logicalchannels into transport channels. The MAC layer can also use Hybrid ARQ(HARQ) to provide retransmission at the MAC layer, to improve linkefficiency. In the control plane, the Radio Resource Control (RRC)protocol layer provides establishment, configuration, and maintenance ofan RRC connection between a wireless device 104 and the base stations102 or core network 106 supporting radio bearers for the user planedata. At the Physical (PHY) layer, the transport channels are mapped tophysical channels.

As illustrated, the wireless devices 104 are distributed throughout thesystem 100, where each wireless device 104 can be stationary or mobile.A wireless device can be referred to as a mobile station, a subscriberstation, a mobile unit, a subscriber unit, a wireless unit, a remoteunit, a handheld mobile device, a remote device, a mobile subscriberstation, an access terminal, a mobile terminal, a wireless terminal, aremote terminal, a handset, a mobile client, a client, or the like.Examples of a wireless device include user equipment (UE) such as amobile phone, a personal digital assistant (PDA), a wireless modem, ahandheld mobile device (e.g., wireless devices 104-1 and 104-2), atablet computer, a laptop computer (e.g., wireless device 104-3), awearable (e.g., wireless device 104-4). A wireless device can beincluded in another device such as, for example, a drone (e.g., wirelessdevice 104-5), a vehicle (e.g., wireless device 104-6), an augmentedreality/virtual reality (AR/VR) device such as a head-mounted displaydevice (e.g., wireless device 104-7), an loT device such as an appliancein a home (e.g., wireless device 104-8), a portable gaming console, or awirelessly connected sensor that provides data to a remote server over anetwork.

A wireless device can communicate with various types of base stationsand network equipment at the edge of a network including macroeNBs/gNBs, small cell eNBs/gNBs, relay base stations, and the like. Awireless device can also communicate with other wireless devices eitherwithin or outside the same coverage area of a base station viadevice-to-device (D2D) communications.

The communication links 114-1 through 114-11 (also referred toindividually as “communication link 114” or collectively as“communication links 114”) shown in system 100 include uplink (UL)transmissions from a wireless device 104 to a base station 102, and/ordownlink (DL) transmissions, from a base station 102 to a wirelessdevice 104. The downlink transmissions can also be called forward linktransmissions while the uplink transmissions can also be called reverselink transmissions. Each communication link 114 includes one or morecarriers, where each carrier can be a signal composed of multiplesub-carriers (e.g., waveform signals of different frequencies) modulatedaccording to the various radio technologies. Each modulated signal canbe sent on a different sub-carrier and carry control information (e.g.,reference signals, control channels), overhead information, user data,etc. The communication links 114 can transmit bidirectionalcommunications using FDD (e.g., using paired spectrum resources) or TDDoperation (e.g., using unpaired spectrum resources). In someimplementations, the communication links 114 include LTE and/or mmWcommunication links.

In some implementations of the system 100, the base stations 102 and/orthe wireless devices 104 include multiple antennas for employing antennadiversity schemes to improve communication quality and reliabilitybetween base stations 102 and wireless devices 104. Additionally oralternatively, the base stations 102 and/or the wireless devices 104 canemploy multiple-input, multiple-output (MIMO) techniques that can takeadvantage of multi-path environments to transmit multiple spatial layerscarrying the same or different coded data.

Computer System

FIG. 2 is a block diagram that illustrates an example of a computersystem 200 in which at least some operations described herein can beimplemented. As shown, the computer system 200 can include: one or moreprocessors 202, main memory 206, non-volatile memory 210, a networkinterface device 212, video display device 218, an input/output device220, a control device 222 (e.g., keyboard and pointing device), a driveunit 224 that includes a storage medium 226, and a signal generationdevice 230 that are communicatively connected to a bus 216. The bus 216represents one or more physical buses and/or point-to-point connectionsthat are connected by appropriate bridges, adapters, or controllers.Various common components (e.g., cache memory) are omitted from FIG. 2for brevity. Instead, the computer system 200 is intended to illustratea hardware device on which components illustrated or described relativeto the examples of the figures and any other components described inthis specification can be implemented.

The computer system 200 can take any suitable physical form. Forexample, the computing system 200 can share a similar architecture asthat of a server computer, personal computer (PC), tablet computer,mobile telephone, game console, music player, wearable electronicdevice, network-connected (“smart”) device (e.g., a television or homeassistant device), AR/VR systems (e.g., head-mounted display), or anyelectronic device capable of executing a set of instructions thatspecify action(s) to be taken by the computing system 200. In someimplementation, the computer system 200 can be an embedded computersystem, a system-on-chip (SOC), a single-board computer system (SBC) ora distributed system such as a mesh of computer systems or include oneor more cloud components in one or more networks. Where appropriate, oneor more computer systems 200 can perform operations in real-time, nearreal-time, or in batch mode.

The network interface device 212 enables the computing system 200 tomediate data in a network 214 with an entity that is external to thecomputing system 200 through any communication protocol supported by thecomputing system 200 and the external entity. Examples of the networkinterface device 212 include a network adaptor card, a wireless networkinterface card, a router, an access point, a wireless router, a switch,a multilayer switch, a protocol converter, a gateway, a bridge, bridgerouter, a hub, a digital media receiver, and/or a repeater, as well asall wireless elements noted herein.

The memory (e.g., main memory 206, non-volatile memory 210,machine-readable medium 226) can be local, remote, or distributed.Although shown as a single medium, the machine-readable medium 226 caninclude multiple media (e.g., a centralized/distributed database and/orassociated caches and servers) that store one or more sets ofinstructions 228. The machine-readable (storage) medium 226 can includeany medium that can store, encoding, or carrying a set of instructionsfor execution by the computing system 200. The machine-readable medium226 can be non-transitory or comprise a non-transitory device. In thiscontext, a non-transitory storage medium can include a device that istangible, meaning that the device has a concrete physical form, althoughthe device can change its physical state. Thus, for example,non-transitory refers to a device remaining tangible despite this changein state.

Although implementations have been described in the context of fullyfunctioning computing devices, the various examples are capable of beingdistributed as a program product in a variety of forms. Examples ofmachine-readable storage media, machine-readable media, orcomputer-readable media include recordable-type media such as volatileand non-volatile memory devices 210, removable flash memory, hard diskdrives, optical disks, and transmission-type media such as digital andanalog communication links.

In general, the routines executed to implement examples herein can beimplemented as part of an operating system or a specific application,component, program, object, module, or sequence of instructions(collectively referred to as “computer programs”). The computer programstypically comprise one or more instructions (e.g., instructions 204,208, 228) set at various times in various memory and storage devices incomputing device(s). When read and executed by the processor 202, theinstruction(s) cause the computing system 200 to perform operations toexecute elements involving the various aspects of the disclosure.

Dynamic Waveform Switcher

FIG. 3 is a block diagram of a representative wireless environment 300where a dynamic waveform switcher function 310 can operate. The dynamicwaveform switching function 310 can operate at the medium access control(MAC) layer together with the scheduler and can be located in aneNB/ng-eNB/gNB or in a standalone network node Environment 300 includesuser devices (e.g., user devices 305 a and 305 b) transmitting andreceiving concurrently from/to multiple base stations, for example,small cell 5G NR base stations 330 a, 330 b, 330 c and macro cell 4G LTEbase station 320.

Carrier aggregation (CA) and dual connectivity (DC) are techniques usedin 4G LTE and 5G NR to allow the UE to utilize the radio resourceswithin multiple component carriers to improve the UE's throughput andreliability. Use of a single transmitter chain in device 305 a/b foraggregated-carrier systems (such as DC and CA) is a common architecturalchoice for various reasons, e.g., power, area, cost, etc. However,several issues can arise when the same transmitter chain is used toprocess the signals destined for different cells and carried bydifferent component carriers, e.g., when several signals close infrequency are processed through non-linear components. One such issue isrelated to intermodulation distortion (IMD).

IMD arises due to non-linear mixing of multiple frequencies especiallythrough high power/gain devices such as power amplifiers in mobiledevices. For example, devices 305 a/b can be configured to operate withdifferent radio access technologies (RATs), for example an LTE RAT andan NR RAT, i.e., in E-UTRAN-NR Dual Connectivity (EN-DC) mode. In thismode, the network or the mobile device can transmit an NR signal inresource blocks allocated around frequency f1, and an LTE signal atresource blocks allocated around frequency f2, where f1>f2, and f1 andf2 are within the same LTE/NR frequency band. Non-linear mixing in thedevice 305 a/b through, for example, the power amplifier (PA) canproduce second order distortion products (IM2) at frequencies f2+f1 andf2−f1, third order intermodulation products (IM3) at frequencies 2f2−f1and 2f1−f2, fifth order intermodulation products (IM5) at frequencies3f2−2f1 and 3f1−2f2, etc. That is, UL transmit signal in the device 305a/b would not only have the intended NR signal around frequency f1 andthe intended LTE signal around frequency f2, the UL transmit signalwould also contain some or all of the above-identified unwantedfrequencies. Typically, the most problematic intermodulation productsare the third order intermodulation products 2f2−f1 and 2f1−f2, because,if f2 and f1 are close in frequency (e.g., in the same LTE/NR band), theresulting upper and lower third order products can fall within that veryLTE/NR band. When the intermodulation products fall within the band ofinterest (i.e., the band carrying the transmitted or received data),this can be a serious problem because the resulting unwanted frequenciescannot easily be filtered out (because the unwanted frequencies overlapwith the intended frequencies f1 and f2). These resulting unwantedfrequencies can leak into the DL receiver paths desensitizing the mainand diversity receivers of devices 305 a/b, and thereby degrading thereceivers' performance. That is, intermodulation distortion affects notjust the UL signal quality, but can also degrades the DL signal quality.The problem with intermodulation distortion tends to be exacerbate thefurther away the mobile devices are from the base station because ULtransmit power tends to be larger, thereby increasing the power of theintermodulation products. The disclosed technology reduces or eliminatessuch IMD products for example in intraband multiple-component-carrier ULtransmit architectures as will be described below.

The dynamic waveform switcher 310 determines or specifies the ULwaveforms or UL access schemes for devices 305 a/b to minimize oreliminate IMD. In some implementations, the dynamic waveform switcher310 can monitor the frequency resources allocated for DL and ULtransmissions by an eNodeB (eNB) for LTE radio access networks (RANs),by an ng-eNB for 5G non-standalone (NSA) access, or by a gNB for 5Gstandalone (SA) access, and determine what UL waveform to specify foruse by devices 305 a/b. To enable this determination, base stations 320and 330 a/b/c can communicate with each other and with the dynamicwaveform switcher 310 via the X2 protocol including the X2 user plane(X2-U) and X2 control plane (X2-C) protocols (the dynamic waveformswitcher 310 can be implemented in any of base stations 320 or 330 a/b/cor in any other node in the core or access network). The communicationbetween base stations can provide the waveform switcher 310 withinformation on the frequency bands scheduled or to be scheduled for DLand UL transmissions. How the dynamic waveform switcher determines orspecifies UL waveforms for use by devices 305 a/b based on allocated orscheduled UL/DL frequency resources is described next.

FIG. 4 is a representative flow diagram 400 illustrating a method fordetermining waveforms for uplink (UL) transmissions. Flow 400 can beimplemented in dynamic waveform switcher 310 of FIG. 3 and/or in one ormore of the eNB, ng-eNB, or gNBs 330 a/b/c described in FIG. 3 and/or adifferent node in the core network or radio access network (collectivelyreferred to as “the network” in the subsequent description).

At block 410, the network identifies or determines UL frequencyresources, e.g., bands or frequencies of UL component carriers (CCs)allocated or scheduled (or to be allocated/scheduled) to the UE forconcurrent UL transmissions (e.g., a first UL CC and a second UL CC for2-carrier DC/CA). The concurrent UL transmissions can be on differentinter-band or intra-band component carriers (i.e., multiple uplinkcomponent carriers for use with DC or CA) where at least one componentcarrier corresponds to a first radio access technology (RAT) and atleast another component carrier corresponds to a second RAT, differentfrom the first RAT.

For example, at block 410, the network can identify scheduled (orto-be-scheduled) UL frequency grants to the UE operating in ULdual-connectivity (DC) mode or UL carrier aggregation (CA) mode. Forexample, the network can determine that one UL frequency for the UE isE-UTRAN/LTE band 3 at ˜1700 MHz and another UL frequency for the UE isNR band n78 at ˜3500 MHz for an EN-DC transmission. Other examples: thenetwork can determine that UL frequencies are LTE band 41 and NR bandn41 at ˜2500 MHz, or LTE band 71 and NR band n71 at ˜600 MHz or ULtransmission at NR band n78 at ˜3.5 GHz and DL transmission at LTE band3 at ˜1.8 GHz. As will be described further below, DC/CA with componentcarriers in B41/n41, for example, can create IMD in DL receiver.

At block 420, the network identifies or determines DL frequencyresources, e.g., DL bands, frequencies, or CCs, allocated or scheduled(or to be allocated/scheduled) to the UE for DL transmission. Theidentified DL frequency resources are frequency resources for use for DLtransmission at the same time as the UL frequency resources are beingused for concurrent UL transmissions. This is because intermodulationdistortion occurs when intermodulation products fall in the sametime-frequency grid as a concurrent reception or transmission so thatthe unwanted/spurious frequencies interfere with the intendedtransmissions/receptions in the affected bands. In some implementations,identifying the UL frequency resources at block 410 and identifying thedownlink (DL) frequency resources at block 420 requires communicationbetween an LTE scheduler and an NR scheduler and between the LTE/NRschedulers and the waveform switcher function 310 (which can, in someimplementations, be part of either scheduler).

At block 430, the network determines a frequency for an IMD productbased on two or more frequencies of the UL frequency resources.Additionally or alternatively, the network can determine the frequencyof IMD products based on the combination of UL and DLallocated/scheduled frequencies. For example, if at block 410 thenetwork determined that one component carrier for UL transmission wasscheduled for LTE frequency band 71 and another component carrier forconcurrent UL transmission was scheduled for NR frequency band n71, thenetwork can determine that IMD products from the UL transmission couldfall within the DL frequency band 71/n71 (which is allocated/scheduledfor use by the UE for DL transmissions).

In some implementations, the network includes a memory (e.g., a databaseor lookup table) that stores the combination of UL frequencies thatcould result in IMD in the corresponding DL frequency. This database ormemory can be located in the dynamic waveform switching function 310 ofFIG. 3 or in another node on the network. Additionally, thedatabase/memory holding the band information can operate at the MAClayer together with the scheduler. In this implementation, the networkcan skip the determination of IMD frequencies at block 430 and determineat block 440, based on the stored UL/DL frequency band combinations,that the risk of IMD is high and thereby dynamically switch or selectsUL waveforms to minimize IMD as described below. In someimplementations, the network can send a query request to the memory(e.g., a processor or server in the network can query the memory ordatabase), where the query request can include a first frequency for afirst UL CC, a second frequency for a second UL CC . . . . (etc., forother UL CCs), and a third frequency for DL CC (etc., for other DL CCs).The processor or server in the network can return a query responseincluding data from the memory indicating a risk or a probability thatthe frequencies in the query request could lead to high IMD (e.g.,frequencies of UL CCs could lead to IMD in DL CC(s)). Based on thisquery response, the network can determine or identify what UL waveformthe UEs can/should use for concurrent UL transmissions as describedbelow.

At block 440, the network determines if the IMD product falls within DLfrequency resources. That is, if the IMD products generated by ULcomponent carriers for use with UL DC or CA fall within the frequencyband allocated or scheduled for DL transmissions to the UE. As describedabove, in some implementations, the network stores the UL/DL frequencycombinations that would lead to high IMD such that at block 440 thenetwork can determine if the scheduled UL/DL frequencies create a highrisk of IMD.

If the risk of IMD is high based on the UL/DL frequencies, the networkdetermines at block 460 that the UE should use a Discrete FourierTransform (DFT)-spread Orthogonal Frequency Multiple Access (OFDM)(DFT-s-OFDM) waveform for UL transmissions. The network can notify theUE to switch to the DFT-s-OFDM waveform if it is currently using aCyclic Prefix (CP) OFDM (CP-OFDM) waveform. For example, the network(e.g., the dynamic waveform switcher function 310 in FIG. 3 ) caninstruct the UE to switch to or remain with DFT-s-OFDM even when networkconditions (e.g., even when channel state information (CSI)) wouldotherwise allow for CP-OFDM UL transmissions).

Conversely, if the risk of IMD is not high based on the UL/DLfrequencies (i.e., if IMD will not fall within a receiving band), thenetwork determines at block 460 that the UE can use a CP-OFDM waveformfor UL transmissions (i.e., UE need not switch to DFT-s-OFDM). That is,the network allows the UE to use CP-OFDM waveforms for UL transmissionsif other criteria (e.g., CSI) does not require the UE to use DFT-s-OFDM.In some implementations, the network instructs the UE to switch to orremain with the CP-OFDM waveform for UL transmissions.

DFT-s-OFDM waveforms are allocated with contiguous physical resourceblock (PRB) thereby avoiding an allocation of PRBs with a largefrequency gap (“devil's horn” PRB allocation) which can create large IMDcomponents which can desensitize the DL receive path. Although theDFT-s-OFDM waveform is better for IMD mitigation, it is less spectrallyefficient than CP-OFDM waveforms. For example, the contiguous PRBallocation of DFT-s-OFDM makes it difficult to allocate multiple UEswith contiguous PRBs unlike CP-OFDM where different UEs can be allocateddifferent non-contiguous PRBs. Thus, the dynamic waveform switcher 310trades off between a high spectral efficiency allocation with CP-OFDM(e.g., allowing for assignment of frequencies based on the radiofrequency (RF) performance of different frequency blocks or CSI feedbackfrom UE) and a low IMD with DFT-s-OFDM. For example, to improve DLefficiency a DFT-s-OFDM waveform can be used because this prevents orreduces the desensitization of the DL receiver. However, use ofDFT-s-OFDM can degrade UL efficiency because of the inflexibility ofcontiguous PRB allocation as described above. To improve UL efficiency aCP-OFDM waveform can be used. In some implementations, the LTE or NRscheduler can allocate contiguous PRBs even for CP-OFDM waveformsthereby removing the need for the mobile device to switch to aDFT-s-OFDM waveform.

For example, with UL CA/DC with 2 component carriers utilizing 2 ULtransmitter paths/chains in the UEs transceiver, certain bandcombinations can result in IMD that falls in the DL receiving path. Forexample, if the first UL component carrier is at frequency f1 and thesecond UL component carrier is at frequency f2, the network determinesat block 440 whether the upper third order intermodulation (IM3) productat 2*f241 (for f2>f1) and the lower IM3 product at 2*f142 (for f2>f1)would fall within DL frequencies. For example, if f1=668 MHz and f2=688MHz (LTE/NR bands 71/n71), the upper intermodulation product would be at708 MHz; and the lower intermodulation product would be at 648 MHz.Because 648 MHz is also in LTE Band 71 and NR band n71 DL band, theconcurrent UL transmissions could interfere with DL transmissionsutilizing the resource blocks at channels occupying 648 MHz. In thiscase, the network can determine at block 460 that the UE should useDFT-s-OFDM to force contiguous PRB allocation which could minimize IMD.

The intermodulation distortion problem discussed above is exacerbatedwhen the different components carriers are in the same band (intraband),particularly for the E-UTRAN/NR dual connectivity (EN-DC) case where thefirst transmission is targeted to the E-UTRAN/LTE radio network and thesecond transmission is targeted to the 5G NR network. This is because,unlike for the CA case where the eNB or ng-eNB can turn off intrabandcomponent carriers and revert to single carrier transmission whenproblems are detected, the EN-DC configuration often requires havingboth carriers active for full-duplex transmit/receive operation.

Additionally, even where simultaneous uplink transmissions on differentintra-band component carriers (e.g., intra-band contiguous EN-DC) maynot be required by 3GPP standards, it is still beneficial for devices toallow for such band combinations as this can lead to better spectralefficiency for the network and better user experience (e.g., higherthroughput). The technology disclosed here allows for UEs to supportsuch non-mandatory dual connectivity cases without any changes to the UEhardware. Furthermore, the systems and methods disclosed herein arefrequency agnostic and so can be adapted for any frequency band, forexample, E-UTRA/LTE band 41 and 5G NR band n41 at 2496-2690 MHz, LTEband 41 and NR band n41 at 2496-2690 MHz, LTE band 3 and NR band n78,and others.

REMARKS

The terms “example”, “embodiment” and “implementation” are usedinterchangeably. For example, reference to “one example” or “an example”in the disclosure can be, but not necessarily are, references to thesame implementation; and, such references mean at least one of theimplementations. The appearances of the phrase “in one example” are notnecessarily all referring to the same example, nor are separate oralternative examples mutually exclusive of other examples. A feature,structure, or characteristic described in connection with an example canbe included in another example of the disclosure. Moreover, variousfeatures are described which can be exhibited by some examples and notby others. Similarly, various requirements are described which can berequirements for some examples but no other examples.

The terminology used herein should be interpreted in its broadestreasonable manner, even though it is being used in conjunction withcertain specific examples of the invention. The terms used in thedisclosure generally have their ordinary meanings in the relevanttechnical art, within the context of the disclosure, and in the specificcontext where each term is used. A recital of alternative language orsynonyms does not exclude the use of other synonyms. Specialsignificance should not be placed upon whether or not a term iselaborated or discussed herein. The use of highlighting has no influenceon the scope and meaning of a term. Further, it will be appreciated thatthe same thing can be said in more than one way.

Unless the context clearly requires otherwise, throughout thedescription and the claims, the words “comprise,” “comprising,” and thelike are to be construed in an inclusive sense, as opposed to anexclusive or exhaustive sense; that is to say, in the sense of“including, but not limited to.” As used herein, the terms “connected,”“coupled,” or any variant thereof means any connection or coupling,either direct or indirect, between two or more elements; the coupling orconnection between the elements can be physical, logical, or acombination thereof. Additionally, the words “herein,” “above,” “below,”and words of similar import can refer to this application as a whole andnot to any particular portions of this application. Where contextpermits, words in the above Detailed Description using the singular orplural number may also include the plural or singular numberrespectively. The word “or” in reference to a list of two or more itemscovers all of the following interpretations of the word: any of theitems in the list, all of the items in the list, and any combination ofthe items in the list. The term “module” refers broadly to softwarecomponents, firmware components, and/or hardware components.

While specific examples of technology are described above forillustrative purposes, various equivalent modifications are possiblewithin the scope of the invention, as those skilled in the relevant artwill recognize. For example, while processes or blocks are presented ina given order, alternative implementations can perform routines havingsteps, or employ systems having blocks, in a different order, and someprocesses or blocks may be deleted, moved, added, subdivided, combined,and/or modified to provide alternative or sub-combinations. Each ofthese processes or blocks can be implemented in a variety of differentways. Also, while processes or blocks are at times shown as beingperformed in series, these processes or blocks can instead be performedor implemented in parallel, or can be performed at different times.Further, any specific numbers noted herein are only examples such thatalternative implementations can employ differing values or ranges.

Details of the disclosed implementations can vary considerably inspecific implementations while still being encompassed by the disclosedteachings. As noted above, particular terminology used when describingfeatures or aspects of the invention should not be taken to imply thatthe terminology is being redefined herein to be restricted to anyspecific characteristics, features, or aspects of the invention withwhich that terminology is associated. In general, the terms used in thefollowing claims should not be construed to limit the invention to thespecific examples disclosed herein, unless the above DetailedDescription explicitly defines such terms. Accordingly, the actual scopeof the invention encompasses not only the disclosed examples, but alsoall equivalent ways of practicing or implementing the invention underthe claims. Some alternative implementations can include additionalelements to those implementations described above or include fewerelements.

Any patents and applications and other references noted above, and anythat may be listed in accompanying filing papers, are incorporatedherein by reference in their entireties, except for any subject matterdisclaimers or disavowals, and except to the extent that theincorporated material is inconsistent with the express disclosureherein, in which case the language in this disclosure controls. Aspectsof the invention can be modified to employ the systems, functions, andconcepts of the various references described above to provide yetfurther implementations of the invention. For example, U.S. Pat. No.10,904,935 (the '935 patent) describes a smart scheduler for IMDavoidance that can use the dynamic waveform switching techniquedescribed herein. Additionally or alternatively, the smart schedulerdescribed in the '935 patent can be used to allocate PRBs to avoid the“devil's horn” non-contiguous PRB allocation without needing to switchthe UL transmission waveform.

To reduce the number of claims, certain implementations are presentedbelow in certain claim forms, but the applicant contemplates variousaspects of an invention in other forms. For example, aspects of a claimcan be recited in a means-plus-function form or in other forms, such asbeing embodied in a computer-readable medium. A claim intended to beinterpreted as a mean-plus-function claim will use the words “meansfor.” However, the use of the term “for” in any other context is notintended to invoke a similar interpretation. The applicant reserves theright to pursue such additional claim forms in either this applicationor in a continuing application.

We claim:
 1. A non-transitory computer-readable storage mediumcomprising instructions recorded thereon that, when executed by at leastone data processor of a system of a wireless communication network,cause the system to perform a method of determining waveforms for uplink(UL) transmissions in a mobile device operating in the wirelesscommunications network, the method comprising: receiving signalsidentifying UL frequency resources scheduled to the mobile device forconcurrent UL transmissions; receiving signals identifying downlink (DL)frequency resources scheduled to the mobile device for DL transmissions;and, automatically determining, based on the UL and DL frequencyresources, a waveform for use by the mobile device for the concurrent ULtransmissions, wherein the determining is based on a frequency of anintermodulation distortion (IMD) product of two or more frequencies ofthe UL frequency resources, wherein the mobile device is to use aDiscrete Fourier Transform (DFT)-spread Orthogonal Frequency DivisionMultiplexing (OFDM) (DFT-s-OFDM) waveform for the concurrent ULtransmissions when the frequency of the IMD product is within the DLfrequency resources, and wherein the mobile device can use a CyclicPrefix (CP) OFDM (CP-OFDM) waveform for the concurrent UL transmissionswhen the frequency of the IMD product is not within the DL frequencyresources.
 2. The non-transitory computer-readable storage medium ofclaim 1, wherein the concurrent UL transmissions comprise dualconnectivity transmissions with multiple uplink component carriers, andwherein each one of the component carriers in the multiple uplinkcomponent carriers is in the same frequency band.
 3. The non-transitorycomputer-readable storage medium of claim 1, wherein the concurrent ULtransmissions comprise multiple-uplink carrier aggregationtransmissions.
 4. The non-transitory computer-readable storage medium ofclaim 1, wherein the concurrent UL transmissions comprise ULtransmissions on different intra-band component carriers.
 5. Thenon-transitory computer-readable storage medium of claim 1, wherein theconcurrent UL transmissions comprise UL transmissions on differentintra-band component carriers and at least one component carrier of theintra-band component carriers corresponds to a first radio accesstechnology (RAT) and at least one component carrier of the intra-bandcomponent carriers corresponds to a second RAT, different from the firstRAT.
 6. The non-transitory computer-readable storage medium of claim 1,wherein the concurrent UL transmissions comprise an LTE UL transmissionand an NR UL transmission.
 7. The non-transitory computer-readablestorage medium of claim 1, wherein the concurrent UL transmissionscomprise UL transmissions on different intra-band component carriers,wherein the different intra-band component carriers comprise componentcarriers in LTE band 41 and component carriers in NR band n41.
 8. Thenon-transitory computer-readable storage medium of claim 1, wherein theconcurrent UL transmissions comprise an LTE UL transmission in LTE band71 at around 600 MHz and an NR UL transmissions in NR band n71 at around600 MHz, and the DL transmissions comprise an LTE DL transmission in LTEband 71 or an NR DL transmission in NR band n71.
 9. The non-transitorycomputer-readable storage medium of claim 1, wherein the DLtransmissions comprise an LTE band 3 DL transmission at around 1.8 GHz,and wherein the concurrent UL transmissions comprise an NR band n78 ULtransmission at around 3.5 GHz.
 10. The non-transitory computer-readablestorage medium of claim 1, wherein the identifying the UL frequencyresources and the identifying the downlink (DL) frequency resourcescomprises communicating between an LTE scheduler and an NR scheduler.11. A method, implemented in a wireless communication network, ofdetermining an uplink (UL) access scheme for use by a user equipment(UE), the method comprising: identifying a first frequency band of afirst UL component carrier (CC) and a second frequency band of a secondUL CC, wherein the first frequency band and the second frequency bandare scheduled for use by the UE for concurrent UL transmissions;identifying a third frequency band of a downlink (DL) CC, wherein thethird frequency band is scheduled for use by the UE for DLtransmissions; and, determining, based on the first frequency band, thesecond frequency band, and the third frequency band, an UL access schemefor use by the UE for the concurrent UL transmissions; wherein thedetermining of the UL access scheme for use by the UE for the concurrentUL transmissions based on the first frequency band, the second frequencyband, and the third frequency band is based on a frequency of anintermodulation distortion (IMD) product of at least the first frequencyband and the second frequency band; wherein the determining of the ULaccess scheme for use by the UE for the concurrent UL transmissionsbased on the first frequency band, the second frequency band, and thethird frequency band, comprises: querying a memory in the wirelesscommunication network; wherein the query includes the first frequencyband, the second frequency band, and the third frequency band; and,receiving a query response, wherein the query response identifies the ULaccess scheme for use by the UE for the concurrent UL transmissions, andwherein the query response relates to a risk for an IMD product at thethird frequency band for the DL transmissions.
 12. The method of claim11, wherein the UL access scheme is at least one of a Discrete FourierTransform (DFT)-spread Orthogonal Frequency Division Multiplexing (OFDM)(DFT-s-OFDM) access scheme or a Cyclic Prefix (CP) OFDM (CP-OFDM) accessscheme.
 13. The method of claim 11, wherein the first UL CC and thesecond UL CC comprise intra-band CCs, the first UL CC corresponds to afirst radio access technology (RAT) and the second UL CC corresponds toa second RAT, different from the first RAT.
 14. The method of claim 11,wherein the first UL CC corresponds to an LTE RAT and the second UL CCcorresponds to an NR RAT.
 15. The method of claim 11, wherein theconcurrent UL transmissions comprise multiple-uplink carrier aggregationtransmissions.
 16. A system configured to determine the uplink (UL)transmission waveform for use by a user equipment (UE) within a wirelesscommunication network of a first radio access technology (RAT) operatingin a dual connectivity mode with a second RAT, different from the firstRAT, the system comprising: at least one hardware processor; and atleast one non-transitory memory, coupled to the at least one hardwareprocessor and storing instructions, which, when executed by the at leastone hardware processor, cause the system to: identify UL frequencyresources scheduled to the UE for concurrent UL transmissions; identifydownlink (DL) frequency resources scheduled to the UE for DLtransmissions; and, determine, based on a frequency of anintermodulation distortion (IMD) product of two or more frequencies ofthe UL frequency resources, a waveform for use by the UE for theconcurrent UL transmissions, wherein the UE is to use a Discrete FourierTransform (DFT)-spread Orthogonal Frequency Division Multiplexing (OFDM)(DFT-s-OFDM) waveform for the concurrent UL transmissions when thefrequency of the IMD product is within the DL frequency resources, andwherein the UE can use a Cyclic Prefix (CP) OFDM (CP-OFDM) waveform forthe concurrent UL transmissions when the frequency of the IMD product isnot within the DL frequency resources, wherein, based on the frequencyof an intermodulation distortion (IMD) product of two or morefrequencies of the UL frequency resources, the waveform for use by theUE for the concurrent UL transmissions comprises: sending a queryrequest to a memory in the wireless communication network, the queryrequest including the UL frequency resources and the DL frequencyresources; receiving a query response from the memory, wherein the queryresponse identifies a risk for an IMD product at a frequency within theDL frequency resources; and, determining, based on the query response,the waveform for use by the UE for the concurrent UL transmissions. 17.The system of claim 16, wherein the concurrent UL transmissions comprisean LTE UL transmission and an NR UL transmission.
 18. The system ofclaim 16, wherein the concurrent UL transmissions comprise ULtransmissions on different intra-band component carriers.